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Water flooding in the cathode channel of the proton exchange membrane fuel cell (PEMFC), which reduce the current density output and affect fuel cell lifetime. Hence, to suppress water flooding, a novel channel is proposed in this study, that is to perforate hole between the cooling channel and cathode channel. A 3D numerical model is used to investigate the influence of the parameters including the hole's dimension, position, numbers, the operation conditions of the PEMFC and the slope angle ( θ ) of the incline cooling channel. The numerical results indicate that the optimal single hole parameters are 0.4 mm long, 0.5 mm wide and 20 mm position, which can maximum the current density output of the PEMFC. Increasing the hole numbers for novel channels can improve water removal. In addition, in comparison with the conventional channel with θ = 0.20° at 1.8 cathode stoichiometry, the H5 (novel channel with five holes) with θ = 0.20° decreases by 43.10% in the maximum water saturation of cathode channel, while increases by 12.54% in current density output. What's more, all the novel channel structure research hardly raises the pressure drop of channels. • A novel channel with a low pressure drop is proposed. • The effect of channel structure parameters is investigated in detail. • Inclined cooling channel design can improve water management capabilities. • The maximum water saturation in the novel channel can be reduced by 43.10%. [ABSTRACT FROM AUTHOR]

In order to solve the problems of uneven component diffusion, weak mass transfer capability and flow field flooding in the conventional flow field of proton exchange membrane fuel cell (PEMFC), and to improve the cell output power. In this paper, a novel folded porous cathode flow field is proposed. A numerical model of three-dimensional multiphase flow is established for comparative study, which reveals the relationship between the component flow characteristics and mass transfer performance of PEMFC. The folding rib structure of the novel flow field triggers gas vortices in the channel and generates secondary flow, improves the mass transfer capability of reactants between the channel and the GDL, and alleviates the drainage problem of the porous layer under the rib. The angle, length and number of folding at the rib of the flow field were mainly changed, and the mass fraction difference coefficient (CV Mi) was used to compare the uniformity of the distribution of the components of the flow field, and the optimal flow field structure was obtained as FP6-7, which increased the current density by 44.9% compared with the traditional linear flow field. For the first time, the secondary flow evaluation criterion absolute vortex flux number J ABS n was introduced to evaluate the mass transfer performance. The influence of fluid flow characteristics on the mass transfer performance is revealed. • The folded porous (FP) flow field improves the mass transfer capacity. • The current density of PEMFC based on FP6-7 flow field was increased by 44.9%. • The mass fraction difference coefficient (CV Mi) was used to evaluate the uniformity of water-air distribution in the flow field. • The absolute vortex flux (J ABS n ) is used for the first time to evaluate the mass transfer characteristics. • The relationship between the flow characteristics of components and the mass transfer capacity in the flow field is revealed. [ABSTRACT FROM AUTHOR]

At high current density, the mass transfer in proton exchange membrane fuel cells (PEMFC) is significantly influenced by the flow field structure. In this paper, a bilateral track flow field (BTFF) is proposed to improve the transverse and longitudinal mass transfer as well as the water removal capacity of PEMFC. The geometry of the BTFF is optimized by orthogonal tests to obtain the optimal combination of geometric parameters and levels. Then using numerical modeling, the impact of the optimized BTFF (BT6) on the efficiency of the PEMFC was examined. The results show that BT6 significantly improves the utilization of the under-rib region by shortening the reactive gas diffusion path length to obtain a more uniform oxygen distribution, and the average oxygen concentration in the midline of the under-rib of the BT6 is increased by 102.60%, furthermore, the current density is increased by 16.32% compared with that of the parallel flow field (case0). In addition, by reducing the cross-sectional area of the gas flow channel, the BT6 has a higher gas flow velocity, which accelerates the removal of cathode liquid water, and the average liquid water saturation in the midline of the under-rib of the BT6 is reduced by 15.26% compared with case0. Finally, by analyzing the net power density of PEMFC, it can be found that the net power density of BT6 is increased by 15.68% compared with case0, which has good practical application value. • A novel bilateral track flow field is proposed and optimized by orthogonal test. • Locally improved structure enhances transverse and longitudinal mass transfer. • The average oxygen concentration under-rib of the optimized flow field has increased by 102.60%. • The optimized flow field net power density has increased by 15.68%. [ABSTRACT FROM AUTHOR]

• An imitated river diversion drainage novel flow field was proposed. • Channel drainage, under-rib porous layers drainage and balanced water management were considered. • The oxygen concentration under the novel flow field was improved by 1.23 times. • The net power of PEMFC with novel flow fields increased by 13.3%. The cathode flow field design of proton exchange membrane fuel cell (PEMFC) could improve water management, avoiding local material failure, increasing oxygen transport and power output. In this study, a novel cathode flow field that imitates river diversion drainage is proposed for settling the issue of channel drainage, under-rib porous layers drainage and balanced water management. A numerical model of the 3D multiphase flow is built for comparative study to reveal the water transport and performance of PEMFC. In the novel flow field, the opened-trap diverts the liquid water of cathode channel to auxiliary channel and increases the gas velocity in cathode channel to drain more water, thereby, 50% liquid water in cathode channel is removed compared to conventional flow field. Micro flume design in auxiliary channel is used to provide the drainage path for under-rib porous layers, meanwhile collected liquid water for convenience to auxiliary channel drainage. The balance water management of novel flow field promotes the downstream drainage and upstream water retention. Effective water management can enhance mass transfer and PEMFC performance. Compares with the conventional flow field, the novel flow field does not increase pressure drop, improves the PEMFC net power and CCL/PEM oxygen concentration by 13.3% and 1.23 times, respectively. [ABSTRACT FROM AUTHOR]